Resilient-backed abrasive stone



Jan. 18, 1966 R. H. HOMEYER 3,229,425

RES ILIENT-BACKED ABRAS IVE STONE Filed Oct. 13, 1964 FIG. 4 FIG. 5

INVENTOR.

ROGER H. HOMEYER BY @W ATTORNEY United States Patent 3,229,425RESILlENT-BACKED ABRASIVE STONE Roger H. Homeyer, Tonawanda, N.Y.,assignor to The Carhorundum Company, Niagara Falls, N.Y., a corporationof Delaware Filed Oct. 13 1964, Ser. No. 403,591 17 Claims. (Cl. 51-211)This is a continuation-in-part of application Serial No. 237,936, filedNovember 15, 1962.

This invention relates to an abrasive article and particularly toarticles adapted for use in improving or sharpening the cutting edge oftools, such as knives, sharpening the points on draftsmans pens, and thelike. More particularly this invention relates to an abrasive sharpeningstone provided with a backing of a resilient, flexible, non-slip member.

In abrasive sharpening stone devices of the past it has been customaryto form the sharpening stones in the shape of an elongated rectangle ofconsiderable thickness. Heretofore, it was considered essential toprovide thick stones, for in order to use such stones it was customaryfor the operator to hold the sharpening stone in his hand whilesharpening the desired edge. However, the disadvantage of holding suchsharpening stones is that during use the fingers of the user areconstantly exposed to contact with the cutting edge being sharpened.

Several alternatives have been previously proposed in order to overcomethe difficulties inherent in the use of hand held sharpening stones. Oneproposed remedy was the use of abrasive sharpening stones having astructure such that the fingers of the user would be protected fromcontact with the cutting edge being sharpened, such as in US. Patent2,674,834. Another proposed remedy was the use of containers or holdersfor the abrasive sharpening stone, such as disclosed in US. Patents1,998,259 and 1,959,647.

Such prior art devices, however, suffered from the disadvantage thatthick abrasive sharpening stones must still be used with the result thatthe sharpening stones were relatively expensive. Also, the use ofcontainers or holders for the stones further added to the cost of thesharpening stone to the consumer. However, the ultimate consumer, otherthan professional tradesmen, will rarely or never use more than a fewtop layers of grain of a sharpening stone. Therefore, the average user,in order to obtain an abrasive sharpening stone, has been required topurchase a relatively expensive, thick stone and if he did not wish tohold the stone during use had to purchase an expensive holding device.

One object of the present invention is to simplify the construction andreduce the cost of manufacture of abrasive sharpening stone devices,thereby permitting marketing of a relatively thin, low cost abrasivearticle.

A further object of the invention is to provide an abrasive sharpeningstone having a greatly improved degree of safety over the abrasivesharpening stone which is normally hand held.

A further object of the invention is to provide improved and simplifiedmeans for preventing movement of the sharpenin stone during use.

A further object of the invention is to provide a relatively thinabrasive sharpening stone secured to a resilient backing member wherebythe backing member is effective to make the thin stone extremelyresistant to accidental breakage.

Further objects and advantages of the invention will be apparent from aconsideration of the following description of the embodiments describedbelow and shown for the purpose of illustration in the accompanyingdrawings, in which:

3,229,425 Patented Jan. 18, 1966 FIGURE 1 is a perspective view of oneembodiment of an improved abrasive article made in accordance with theinvention;

FIGURE 2 is a similar view of another embodiment of the presentinvention;

FIGURE 3 is a perspective view of the embodiment of the invention shownin FIGURE 2 in which the resilient member surrounding the sharpeningstone is partially folded back from the abrading surface of thesharpening stone.

FIGURE 4 is a perspective view of the embodiment of the inventionillustrated in FIGURE 2 in which the resilient member has beencompletely removed from the abrading surface of the abrasive sharpeningstone; and

FIGURE 5 is a perspective view of another embodiment of the invention.

While the abrasive sharpening stone and the resilient backing memberhave been principally illustrated in a rectangular, flat form, it willbe understood that the invention may be embodied in other shapes andforms, such as in an abrasive sharpening stone of circular shape securedto a backing of a resilient member more or less conforming in shape tothe circular form of the stone as shown in FIGURE 5.

In the embodiment illustrated in FIGURE 1 the sharpening stone is arelatively thin, rigid, brittle abrasive plate designated by the numeral1 and a resilient, flexible, non-slip, backing member therefor isdesignated by the numeral 2. An adhesive layer 3 firmly secures therectangular abrasive sharpening stone 1 to the resilient backing member2.

In the embodiment of the invention shown in FIG- URES 2 to 4, inclusive,the numeral 10 designates an abrasive sharpening stone similar to theone indicated at 1 in FIGURE 1. This stone has a pair of substantiallyparallel fiat surfaces and is surrounded by a resilient, flexible,non-slip member 11, which is substantially as wide as the sharpeningstone. The resilient member 11 comprises an upper layer 12 which iscontiguous with the upper fiat surface 16 of the sharpening stone and abottom layer 13 which is firmly secured to the bottom surface of theabrasive sharpening stone by means of a suitable adhesive layer 14. Theresilient member, in this embodiment of the invention is formed as anelongated strip and the ends thereof are secured to the bottom flatsurface of the sharpening stone in abutting relation as shown at 15 sothat the resilient member forms a continuous band surrounding the upperand lower flat surfaces and the ends of the abrasive sharpening stone,but is secured thereto only at the lower surface of the sharpeningstonev While the ends of the resilient member are shown in FIGURES 2 to4, inclusive, in abutting relation at approximately the midpoint of thebottom flat surface of the sharpening stone, it will be understood thatthe ends of the resilient member may abut one another at any point onthe bottom fiat surface. Furthermore, the ends of the resilient membermay be secured to the bottom flat surface of the sharpening stone inadjoining relation, so that the ends are not in contact with oneanother.

In the embodiment of the invention shown in FIGURE 2 the resilient,non-slip member 11 serves to protect the relatively thin, rigid,brittle, abrasive sharpening stone 10 from breakage during handling andstorage. The shock absorbing effect of the resilient member protects thethin, rigid, stone from accidental breakage and fracture. Such anabrasive article can even be dropped onto a cement or concrete floorwithout breaking the abrasive stone. The reduced mass of the thinsharpened stone contributes to its resistance to breakage in such case.

In order to use the abrasive surface of the sharpening stone, the upperlayer 12 of the resilient member is merely folded back from the uppersurface of the abrasive sharpening stone, as shown in FIGURES 3 and 4,thereby exposing the upper flat surface 16 of the sharpening stone. Whenthe upper layer 12 of the resilient member is completely folded backupon itself, the entire upper flat surface 16 of the abrasive sharpeningstone is thereby exposed and available for use. The upper layer 12 ofthe resilient, non-slip member, upon being folded back from the uppersurface of the sharpening stone is folded below the bottom layer 13 ofthe rsilient member, as shown in FIGURE 4, and thereby becomes a bottomsupporting layer for the abrasive stone. Thus the abrasive sharpeningstone is cushioned by a double layer member of a resilient, flexible,non-slip material. When the abrasive article is in the form shown inFIGURE 4, the double layered resilient member may be placed upon asurface such as a bench, table, desk and the like and the edge to besharpened is applied to the upper surface of the stone in the customarymanner. The nature of the resilient material is such that considerablepressure can be exerted on the stone and the resilient supporting layerswill hold the abrasive stone firmly in position.

In a specific embodiment of the invention a rigid, abrasive sharpeningstone, for example, one employing fine grit silicon carbide particlesbonded with a conventional vitrified bond, produced by any conventionalor known practice such as described in US. Patent No. 2,158,034, andhaving a thickness of about one-quarter inch was adhesively secured to afoamed rubber backing member having substantially the same dimentions asthe sharpening stone and having a thickness of about onequarter inch. Aconventional neoprene base contact cement, such as that sold by theArmstrong Cork Company under the identification number 25 3N-30, wasused to secure the backing member to the sharpening stone.

The sharpening stone used in the invention may be either a naturalabrasive stone, such as the commonly known Arkansas stone, or it may beformed of bonded artificial abrasives such as particles of siliconcarbide, aluminum oxide, corundum, emery and the like. The bond employedin the formation of the sharpening stone may vary in accordance with theproperties desired. While in general ceramic bonds are preferred, insome cases metal or organic bonds of well known types may be used.

The sharpening stone may be made in any shape or configuration desired.However, rectangular aid circular shapes are preferred. Thus, in placeof the rectangular shaped sharpening stone shown in FIGURE 1, arelatively thin, rigid, brittle circular sharpening stone may be firmlysecured to a resilient, non-slip member. Such an embodiment isillustrated in FIGURE 5 where the numeral 17 designates a thin, rigid,brittle, relatively thin, circular shapening stone. The stone 17 isattached by a layer 18 of suitable adhesive to a resilient, flexible,nonslip backing member 19. Similarly, relatively thin, rigid, brittlesharpening stones of circular shape having substantially parallel flatsurfaces may be formed and encompassed in a resilient, flexible,non-slip member, as in the embodiment shown in FIGURES 2-4, so that theresilient member surrounds a plurality of surfaces of the stoneincluding the parallel flat surfaces and protects the edges of thesharpening stone.

As indicated above, the sharpening stones with which the invention isconcerned'are relatively thin as compared to conventional stone.Generally, the thickness of the stones is in the range of from about/s-inch to about /z-inch thick, the thickness employed being determinedby the area of the sharpening stone, stones of larger area normallybeing thicker than smaller stones. However, stones having a somewhatgreater thickness are considered to be within the scope of theinvention. The dimensions of the rigid, brittle sharpening stone willvary according to the intended use, manufacturing techniques, costadvantage and so forth. In any case, the present invention makespossible the use of sharpening stones that are relatively thin ascompared to such stones designed for use unmounted without danger ofbreaking the stone in use or of cutting the hand of the user. This isdue to the presence of the resilient backing which functions as anon-slip, stable base that supports the stone in a flat immovableposition on a surface during sharpening operations and thus eliminatesthe necessity of holding the stone, with the fingers or otherwise,during such operations.

The resilient backing member may have substantially the same dimensionsas the abrasive stone and in the embodiment of the invention shown inFIGURES 2 to 4, inclusive, should be of a length sufficient to encompassthe upper and lower flat surfaces and the ends of the sharpening stone.In a modification of the invention shown in FIGURES 2 to 4, inclusive,the resilient member may be in the form of an endless band of resilient,flexible, non-slip material which encompasses the sharpening stone andwhich is firmly secured to only one flat surface of the abrasivesharpening stone.

In the embodiment of the invention illustrated in FIG- URES 2 to 4,inclusive, the backing member in addition to being resilient andflexible preferably is stretchable to some extent. This facilitates theremoval of the upper layer of the resilient member from the upper flatsurface of the sharpening stone. The material to be used for the backingmember should also have the characteristic of being non-slipping, so asto hold the relatively thin, rigid, brittle sharpening stone in positionwhen placed on a smooth or rough surface when pressure is applied to theupper flat surface of the sharpening stone in a direction parallelthereto as occurs when tool edges are sharpened thereon. Material of thetype of foam or sponge rubber, a flexible, foamed plastic material suchas polyurethane foam, polyvinyl foam, and the like, or a felt materialsuch as hair or sisal felt have been found to be suitable materials forthe resilient backing member. When a stretchable member is desired,however, foam rubber is preferred.

Preferably the thickness of the resilient backing member is in the rangeof from -inch to %-inch thick, but a resilient member having a somewhatgreater thickness is considered to be within the scope of the invention.

Generally, a rubber or synthetic rubber base cement has been found to besuitable for most purposes for securing the resilient backing member tothe abrasive sharpening stone. However, other materials capable ofsecuring the backing member to the sharpening stone, such as epoxy resincements, phenolic resin cements, rubber modified resin cements, and thelike are suitable. The adhesive material may be applied to either orboth contacting surfaces over the entire surfaces or over portions ofone or both surfaces.

While the invention has been described in connection with specificembodiments thereof, it will be understood that it is capable of furthermodification, and this application is intended to cover any variations,uses or adaptations of the invention. It will therefore be recognizedthat the invention is not to be considered as limited to the preciseembodiments shown and described but is to beinterpreted as broadly aspermitted by the appended claims.

I claim:

1. An abrasive article comprising a flat, rigid, brittle abrasivesharpening stone of bonded abrasive particles, said stone being adaptedfor safe manual operation and said stone being relatively thin incomparison with conventional sharpening stones and having a thickness ofthe. order of /8-iI1Ch to /2-inch; and a backing member of resilient,flexible, non-slip material adhesively secured to the rear surface ofsaid stone and functioning as a stable, non-slip base for holding saidstone immovable in a flat sharpening position on a surface.

2. An abrasive article as defined in claim 1 in which said stone hassubstantially flat top and bottom surfaces and said backing member has apair of substantially flat surfaces one of which is adhesively securedto the bottom of said stone.

3. An abrasive article as defined in claim 2 in which the flat surfaceof said backing member secured to the bottom of said stone issubstantially the same size and shape as said bottom of said stone.

4. An abrasive article as defined in claim 1 in which said sharpeningstone is circular.

5. An abrasive article as defined in claim 3 in which said sharpeningstone is circular.

6. An abrasive article as defined in claim 1 in which the resilient,flexible, non-slip member is a material selected from the groupconsisting of foam rubber, sponge rubber, flexible polyurethane foam,flexible polyvinyl foam, hair felt and sisal felt.

7. An abrasive article as defined in claim 3 in which the resilient,flexible, non-slip member is a material selected from the groupconsisting of foam rubber, sponge rubber, flexible polyurethane foam,flexible polyvinyl foam, hair felt and sisal felt.

8. An abrasive article as defined in claim 4 in which the resilient,flexible, non-slip member is a material se lected from the groupconsisting of foam rubber, sponge rubber, flexible polyurethane foam,flexible polyvinyl foam, hair felt and sisal felt.

9. An abrasive article comprising a relatively thin, rigid, brittleabrasive sharpening stone having a pair of substantially parallel, flatsurfaces in which one of said surfaces is secured to a surface of alayer of a resilient member which surrounds a plurality of surfaces ofsaid stone including the parallel flat surfaces thereof and protects theedges of said stone, the resilient member being capable of being removedfrom all surfaces of the sharpening stone except the surface to which itis secured.

it). An abrasive article which comprises a continuous band of aresilient, flexible, non-slip member having a pair of substantially flatparallel surfaces and a substantially rectangular, relatively thin,rigid, brittle abrasive sharpening stone having a pair of substantiallyparallel flat surfaces, in which one of said surfaces of said member isadhesively secured to one of said surfaces of said sharpening stone,said resilient member surrounding a plurality of surfaces of said stoneincluding said parallel flat surfaces and protecting the edges of saidstone, whereby the resilient member is capable of being removed from allsurfaces of the sharpening stone except the surface to which it issecured.

11. An abrasive article which comprises a relatively 6 thin rigid,brittle abrasive sharpening stone having a pair of substantiallyparallel flat surfaces, a resilient, flexible, non-slip member which isat least substantially as wide as said abrasive stone, and means forsecuring said member to one of said surfaces of the abrasive sharpeningstone, in which said member forms a continuous band which surrounds aplurality of surfaces of said stone including the parallel flat surfacesthereof and protects the edges of said stone and is capable of beingremoved from all surfaces and edges of the sharpening stone except thesurface to which it is secured.

12. An article as described in claim 11 in which the abrasive sharpeningstone is a relatively thin, rigid, brittle circular-shaped stone.

13. An article as described in claim 11 in which the abrasive sharpeningstone is a relatively thin, rigid, brittle substantiallyrectangular-shaped stone.

14. An article as described in claim 11 in which the abrasive sharpeningstone has a thickness of from about As-inch to /2-inch.

15. An abrasive article which comprises a thin, rigid, brittle bondedabrasive sharpening stone, said stone having a pair of substantiallyparallel flat surfaces consisting of an upper flat surface and a lowerflat surface and end edge surfaces, and a resilient, flexible, non-slipmember surrounding said upper and lower flat surfaces and said end edgesurfaces of said stone and being secured to said lower flat surface,said member being capable of being removed from all surfaces of saidstone except the surface to which it is secured.

16. The abrasive article as defined in claim 15 in which the resilient,flexible, non-slip member comprises an upper layer which is contiguouswith the upper flat surface of said stone, and a bottom layer which issecured to the lower flat surface of said stone.

17. The abrasive article as defined in claim 15 in which the resilient,flexible, non-slip member is an elongated strip, the ends of which aresecured to said lower flat surface of said stone.

References Cited by the Examiner UNITED STATES PATENTS 1,639,204 8/1927Welch 512l1 1,852,223 4/1932 Stockert 51-204 X 1,949,804 3/1934 Love51-2l1.l 2,398,890 4/1946 Howard Sl209 ROBERT C. RIORDON, PrimaryExaminer.

LESTER M. SWINGLE, Examiner.

1. AN ABRASIVE ARTICLE COMPRISING A FLAT, RIGID, BRITTLE ABRASIVESHARPENING STORE OF BONDED ABRASIVE PARTICLES, SAID STONE BEING ADAPTEDFOR SAFE MANUAL OPERATION AND SAID STONE BEING RELATIVELY THIN INCOMPARISON WITH CONVENTIONAL SHARPENING STONES AND HAVING A THICKNESS OFTHE ORDER OF 1/8-INCH TO 1/2-INCH; AND A BACKING MEMBER OF RESILIENT,FLEXIBLE, NON-SLIP MATERIAL ADHESIVELY SECURED TO THE REAR SURFACE OFSAID STONE AND FUNCTIONING AS A STABLE, NON-SLIP BASE FOR HOLDING SAIDSTONE IMMOVABLE IN A FLAT SHARPENING POSITION ON A SURFACE.